package lanQiaoBei.基础算法.sort;
import java.util.*;
/*
* “求一个数的发三次方根”——浮点二分
* */
public class P7 {
    public static void main(String[] args)throws Exception {
          Scanner scanner= new Scanner(System.in);
          double x=scanner.nextDouble();
          double l=-10000,r=10000;
          while (r-l>1e-8){
                double mid=(l+r)/2;
                if((mid*mid*mid)>=x)r=mid;
                else l=mid;
          }
         System.out.println(l);
    }
}
